In a vehicle or the like, when power and a rotation rate become large, a torsional vibration and a bending vibration with respect to a crank shaft are increased. Because of this, there is employed a technique in which a rubber damper or the like is provided at a shaft end of the crank shaft, to suppress the torsional vibration and the bending vibration.
For example, JP H3-140653 A discloses a variable spring constant-type rotation shaft vibration dumper in which a circular ring shaped inertial body is placed on an outer circumferential portion of a damper disc with rubber therebetween, and which comprises a spring end fixation unit that simultaneously connects a spring to the inertial body and the damper disc at a set rotation rate.
JP 2015-135179 A discloses a drive force transmission apparatus comprising a first rotation shaft, a second rotation shaft, an elastic member, and a vibration element, wherein one end of the elastic member is fixed at a position deviated from an axial center of the second rotation shaft, the other end of the elastic member is fixed on the vibration element, and the vibration element can take either a state where the vibration element is connected to the first rotation shaft or a state where the vibration element is not connected to the first rotation shaft.
In addition, in the related art, a device for suppressing a torque variation of an internal combustion engine or the like is known, such as a vibration damper described in JP 2011-208774 A.
In the variable spring constant-type damper of the related art, the entire rigidity of a torsional damper is changed by a fixation position or an applied pressure of the spring itself. Therefore, a range where the rigidity can be varied is limited, and there have been problems in that the structure becomes complicated and the timing for making the rigidity variable is restricted. In addition, in order to limit the torque when a large force is applied to the spring, a frictional member must be provided in series with the spring.
In addition, in the drive force transmission device of the related art, because a structure for releasing the drive force is necessary, there is a problem in that the size of the device becomes large. Moreover, in a typical damper, the rigidity is not variable. Further, in the variable spring constant-type damper, a range where the rigidity can be varied is limited, and there have been problems in that the structure becomes complicated, and the timing for making the rigidity variable is restricted. In addition, in order to limit the torque when a large force is applied to the spring, a torque limiter such as a frictional member must be provided in series with the spring.
Further, in the torque variation suppressing apparatus of the related art, the elastic element and a mass (massive portion) for suppressing the torque variation are provided on a rotation transmission system, thereby increasing the overall weight of the rotation transmission system.